Resealable Leak-Resistant Containers Having A Pressed Pulp Tray With A Thermoformed Plastic Lid

ABSTRACT

A leak-resistant pulp container with a plastic lid is disclosed, including a tray formed of molded pulp and having a boom and a sidewall forming an interior volume. The tray has an edge extending peripherally outward from an upper edge of the sidewall, and the tray edge has an outer portion. The container further includes a plastic lid having an edge extending peripherally outward therefrom, and the lid edge having an outer portion.

CROSS-REFERENCE TO RELATED APPLICATION

This is a U.S. national stage of application No. PCT/US2014/028541,filed on 14 Mar. 2014, which claims the benefit of U.S. ProvisionalPatent Application No. 61/799,008, filed on 15 Mar. 2013, both of whichare hereby incorporated by reference in their entireties.

FIELD OF THE INVENTION

The disclosed embodiments relate to resealable containers withleak-resistant features for storing food, liquids, and various otheritems. In particular, the disclosed embodiments relate to resealableleak-resistant containers having a molded pulp tray with a plastic lid.

BACKGROUND OF THE INVENTION

The use of plastic disposable containers and trays for packaging,distributing, food are widespread in the marketplace. There is a needfor containers that are easy open and close, but at the same time,resist leaks. This is especially true for containers designed forliquids, e.g., soup containers. The leak-resistance must be maintainedeven when the container is accidentally tilted during transportation andhandling so that the liquid contained therein reaches the seam where thebottom (i.e., tray) and lid of the container are joined.

Containers having a tray formed of molded pulp are often seen as anenvironmentally-friendly option. However, the physical properties ofpulp material and its production processes can make it difficult toproduce a pulp container with leak-resistant properties.

For example, it can be difficult to manufacture a pulp container with asmall “draft angle,” which is the angle of the upper edge of thecontainer wall relative to vertical. Due to the nature of themanufacturing processes of pulp containers, small draft angles cancreate an array of production and quality problems, such as unevendistribution of fibers in the produced part, inconsistent part geometry,damage to manufacturing equipment, etc. A typical paper container, onthe other hand, such as a soup cup, may have a draft angle of between 5and 7 degrees. This relatively small draft angle allows the containerwall to exert a greater force on the lid when it is wedged into theupper portion of the container wall to seal the container, i.e., becausethe force exerted by the container wall is largely in a horizontaldirection. This helps maintain a tighter seal for the paper container.Similarly, plastic containers may be formed with an equally small draftangle relatively easily.

A container having a small draft angle is difficult to achieve in amolded pulp process, because a larger, i.e., wider, draft angletypically must be used with pulp materials due to the nature of the pulpmolding process. The use of a wider draft angle results in a greaterportion of the force exerted by the container walls on the lid beingdirected in a vertical direction of the container when upright, i.e., adirection which tends to produce an upward force on the lid. Therefore,a conventional pulp container can be harder to seal in a leak-resistantmanner.

Another physical property of pulp material which can make aleak-resistant container difficult to manufacture is the relative lackof flexibility of molded pulp. The lack of flexibility arises from thecharacteristics of the natural fibers, which tend not to stretch verymuch on their own or when molded together. This lack of flexibilitymeans that certain geometries, known as “undercuts,” cannot easily beused in pulp containers. An undercut is a portion, e.g., an edgeportion, of a container which decreases in width as the sidewall of thecontainer extends toward its upper edge. In a container lackingundercuts, on the other hand, the width of the container increasescontinuously as the sidewall extends toward its upper edge. An undercutcan be achievable and useful in creating an interconnection between acontainer tray and lid, such as in a container made entirely of flexiblematerials, such as plastic. However, a pulp container part havingundercuts will likely tear as it is removed from the mold due to itslack of flexibility and also due to inherent texture characteristics ofthe pulp arising from its manufacturing process. This characteristiceffectively limits the geometries which can be used in a pulp containerand makes it more difficult to achieve a leak-resistant design.

SUMMARY OF THE INVENTION

The disclosed embodiments provide leak-resistant, resealable containers,e.g., for food products. The disclosed embodiments include containersdesigned for liquids, e.g., soup containers, and the like. Theleak-resistance is maintained even when the container is tilted so thatthe liquid contained therein reaches the seam where the bottom (i.e.,tray) and lid of the container are joined.

The disclosed embodiments also provide various shapes of the lid andtray rims which form locking mechanisms to keep the lid attached to thebottom portion of the container.

In one aspect, the present invention provides a leak-resistant pulpcontainer with a plastic lid, including a tray formed of molded pulp andhaving a bottom and a sidewall forming an interior volume. The tray hasan edge extending peripherally outward from an upper edge of thesidewall, and the tray edge having an outer portion. The containerfurther includes a plastic lid having an edge extending peripherallyoutward therefrom, and the lid edge having an outer portion. The lidedge and the tray edge each has a corresponding peripheral channelconfigured so that one of the peripheral channels is received in theother of the peripheral channels to secure the lid to the tray, each ofthe peripheral channels comprising an inner wall and an outer walljoined by a horizontal channel wall. The outer wall of the peripheralchannel of the lid edge has a protrusion which mates with the outerportion of the tray edge to create an interference fit between the lidedge and the tray edge to secure the lid to the tray.

Embodiments of the present invention may include one or more of thefollowing features.

The inner wall of the peripheral channel of the tray edge may have asealing surface which presses against a corresponding sealing surface ofthe inner wall of the peripheral channel of the lid edge when the lid issecured to the tray, thereby forming a leak-resistant seal between thelid edge and the tray edge. The lid edge may be configured so that theouter wall of the peripheral channel of the lid edge applies force tothe outer portion of the tray edge to force the sealing surface of thetray edge against the sealing surface of the lid edge. The sealingsurfaces of the lid edge and the tray edge may extend to include atleast a portion of the horizontal channel walls of the lid edge and thetray edge. The inner wall of the peripheral channel of the lid edge andthe inner wall of the peripheral channel of the tray edge may bedimensioned to at least partially overlap in a cross-sectional plane,thereby forcing the sealing surface of the tray edge against the sealingsurface of the lid edge when the lid is secured to the tray.

The protrusion of the outer wall of the peripheral channel of the lidedge may have a lower lip which extends inward to keep the outer portionof the tray edge in place in the protrusion, thereby acting to securethe lid to the tray. The lower lip of the protrusion of the outer wallof the peripheral channel of the lid edge may be formed in separateperipheral segments around the periphery of the lid.

The inner wall of the peripheral channel of the tray edge may form adraft angle with respect to a vertical direction of the container, whenupright, of between about 8 degrees and about 12 degrees. The draftangle of the inner wall of the peripheral channel of the tray edge maybe between about 10 degrees and about 12 degrees.

The outer portion of the tray edge may be substantially flat in ahorizontal plane of the container when upright. A tab may extend fromthe lid edge and beyond the tray edge. The tray and the lid each mayhave a substantially oval shape.

The lid may be formed of any of the following plastic materials: highdensity polyethylene (HDPE), polyethylene terephthalate (PET),polypropylene (PP), polystyrene (PS), and polylactic acid (PLA). The lidmay be formed by a thermoforming process. The lid may be formed by aninjection molding process.

In another aspect, the present invention provides a leak-resistant pulpcontainer with a plastic lid, including a tray formed of molded pulp andhaving a bottom and a sidewall forming an interior volume. The tray hasan edge extending peripherally outward from an upper edge of thesidewall, the tray edge having an outer portion. The container furtherincludes a plastic lid having an edge extending peripherally outwardtherefrom, the lid edge having an outer portion. The lid edge and thetray edge each has a corresponding lock portion configured so that oneof the lock portions mates with the other of the lock portions to securethe lid to the tray. The lid edge and the tray edge each has acorresponding seal portion configured so that one of the seal portionspresses against the other of the seal portions when the lid is securedto the tray, thereby forming a leak-resistant seal between the lid edgeand the tray edge.

Embodiments of the present invention may include one or more of thefollowing features.

The seal portions of the lid edge and the tray edge may be formed in aninner portion of the lid edge and the tray edge with respect to the lockportions of the lid edge and the tray edge. The lock portion of the lidedge may include an outer wall having a protrusion which mates with theouter portion of the tray edge to create an interference fit between thelid edge and the tray edge to secure the lid to the tray. The lid edgemay be configured so that the outer wall of the lock portion appliesforce to the outer portion of the tray edge to force the seal portion ofthe tray edge against the seal portion of the lid edge.

BRIEF DESCRIPTION OF THE DRAWINGS

The above and/or other aspects and advantages will become more apparentand more readily appreciated from the following detailed description ofthe disclosed embodiments taken in conjunction with the accompanyingdrawings of which:

FIG. 1 shows a perspective view of an embodiment of a resealableleak-resistant container having a molded pulp tray with a plastic lid.

FIG. 2 shows a perspective view of the molded pulp tray of the containerof FIG. 1.

FIG. 3 shows a top plan view of the container of FIG. 1.

FIG. 4 shows a top plan view of a resealable leak-resistant containerhaving a square shape.

FIG. 5 shows a top plan view of a resealable leak-resistant containerhaving a round shape.

FIG. 6 shows a vertical cross-sectional view of the container of FIG. 1taken along line A-A depicted in FIG. 3.

FIG. 7 shows an enlargement of Region B of FIG. 6 showing the peripheraledge of the lid interlocking with the peripheral edge of the tray.

FIG. 8 shows a theoretical view of the enlargement of Region B of FIG. 6showing the dimensional overlap of the peripheral edge of the lid andthe peripheral edge of the tray, as designed.

DETAILED DESCRIPTION

FIGS. 1-3 show an embodiment of a resealable leak-resistant container100 having a molded pulp tray 110 with a plastic lid 120. The tray 110has a bottom 115 and a sidewall 117 forming an interior volume (see,e.g., FIG. 2). The tray 110 has an edge 125 extending peripherallyoutward from an upper edge of the sidewall 117. The tray 110 and the lid120 each has a substantially oval shape (see, e.g., FIG. 3). Although,other shapes are also possible, such as square (see FIG. 4) or round(see FIG. 5). A tab 135 may extend from the lid edge 130 and beyond thetray edge 125. The inward facing lip portions 185 are described below inthe discussion of FIG. 7.

The lid 120 of the leak-resistant pulp container 100 may be formed ofany of the following plastic materials: high density polyethylene(HDPE), polyethylene terephthalate (PET), polypropylene (PP),polystyrene (PS), and polylactic acid (PLA). The plastic lid can beformed by various processes, including, for example, thermoforming andinjection molding.

The tray 110 of the leak-resistant pulp container 100 is formed of pulpwhich has undergone a pressing and molding process. The pulp may beformed of various fibrous materials, such as, for example, Bagasse,bamboo, wheat straw, wood, etc. The pulp is processed by pouring asuspension of pulp material and liquid (e.g., water) into a mold havinga cavity with a number of holes and which is covered with a very finemesh. The liquid is suctioned away, and the collected fibers on the meshare pressed between two corresponding heated molds to squeeze outadditional liquid. In further steps, additional pressing and heatprocesses may be applied to form and dry the final parts.

FIG. 6 shows a vertical cross-sectional view of the container 100 ofFIG. 1 (when upright) taken along line A-A depicted in FIG. 3. It can beseen in this view that the lid edge 130 and the tray edge 125 each has acorresponding peripheral channel 140 configured so that one of theperipheral channels is received in the other of the peripheral channelsto secure the lid 120 to the tray 110. In the embodiment depicted, theperipheral channel 140 of the tray edge 125 is received into theperipheral channel 140 of the lid edge 130.

FIG. 7 shows an enlargement of Region B of FIG. 6 showing the peripheraledge of the lid 130 interlocking with the peripheral edge of the tray125. The peripheral channel 140 of the lid edge 130 has an inner wall145 and an outer wall 150 joined by a horizontal channel wall 155.Similarly, the peripheral channel 140 of the tray edge 125 has an innerwall 160 and an outer wall 165 joined by a horizontal channel wall 170.In the embodiment depicted, the tray edge 125 has an outer portion 180which is substantially flat in a horizontal plane of the container 100.The plastic lid 120 also has an edge extending peripherally outwardtherefrom which has a substantially flat outer portion 182.

The outer wall 150 of the peripheral channel 140 of the lid edge 130 hasa protrusion 175 which mates with the outer portion 180 of the tray edge125 to create an interference fit between the lid edge 130 and the trayedge 125 to secure the lid 120 to the tray 110. The inner wall 160 ofthe peripheral channel 140 of the tray edge 125 has a sealing surface162 which presses against a corresponding sealing surface 147 of theinner wall 145 of the peripheral channel 140 of the lid edge 130 whenthe lid 120 is secured to the tray 110, thereby forming a leak-resistantseal between the lid edge 130 and the tray edge 125. The sealingsurfaces (147, 162) of the lid edge 130 and the tray edge 125 may extendto include at least a portion of the horizontal channel walls (155, 170)of the lid edge 130 and the tray edge 125.

The inner wall 160 of the peripheral channel 140 of the tray edge 125may form a draft angle with respect to a vertical direction of thecontainer (when upright) of between about 8 degrees and about 12degrees, or between about 10 degrees and about 12 degrees. In theembodiment depicted, the draft angle is about 12 degrees. The draftangle of the inner wall 162 of the lid edge 130 is substantially equalto that of the inner wall 160 of the tray edge 125 in order to achieve astrong seal.

The protrusion 175 of the outer wall 150 of the peripheral channel 140of the lid edge 130 has a lower lip 185 which extends inward to keep theouter portion 180 of the tray edge 125 in place in the protrusion 175,thereby acting to secure the lid 120 to the tray 110. The lower lip 185may be formed continuously around the periphery of the lid 120 or inseparate peripheral segments (see, e.g., FIG. 1).

FIG. 8 shows a theoretical view of the enlargement of Region B of FIG. 6showing the dimensional overlap, i.e., interference fit, of theperipheral edge of the lid 130 and the peripheral edge of the tray 125,as designed. The inner wall 145 of the peripheral channel 140 of the lidedge 130 and the inner wall 160 of the peripheral channel 140 of thetray edge 125 are dimensioned to at least partially overlap in across-sectional plane. This, in turn, helps force the sealing surface162 of the tray edge 125 against the sealing surface 147 of the lid edge130 when the lid 120 is secured to the tray 110. The view depicted istheoretical, in the sense that the dimensionally-overlapping portionswill actually deform slightly and abut each other when the container isclosed.

In addition, the lid edge 130 may be configured so that the outer wall150 of the peripheral channel 140 of the lid edge 130, and in particularthe protrusion 175 formed therein, applies force to the outer portion180 of the tray edge 125 to force the sealing surface 162 of the trayedge 125 against the sealing surface 147 of the lid edge 130. This maybe done by dimensioning the outer portion 180 of the tray edge 125 sothat it has dimensional overlap, i.e., an interference fit, with theprotrusion 175, as shown in FIG. 8.

Although example embodiments have been shown and described in thisspecification and figures, it would be appreciated by those skilled inthe art that changes may be made to the illustrated and/or describedexample embodiments without departing from their principles and spirit.

What is claimed is:
 1. A leak-resistant pulp container with a plasticlid, comprising: a tray formed of molded pulp and having a bottom and asidewall forming an interior volume, the tray further comprising an edgeextending peripherally outward from an upper edge of the sidewall, thetray edge having an outer portion; and a plastic lid having an edgeextending peripherally outward therefrom, the lid edge having an outerportion, wherein the lid edge and the tray edge each has a correspondingperipheral channel configured so that one of the peripheral channels isreceived in the other of the peripheral channels to secure the lid tothe tray, each of the peripheral channels comprising an inner wall andan outer wall joined by a horizontal channel wall, and wherein the outerwall of the peripheral channel of the lid edge has a protrusion whichmates with the outer portion of the tray edge to create an interferencefit between the lid edge and the tray edge to secure the lid to thetray.
 2. The leak-resistant pulp container of claim 1, wherein the innerwall of the peripheral channel of the tray edge has a sealing surfacewhich presses against a corresponding sealing surface of the inner wallof the peripheral channel of the lid edge when the lid is secured to thetray, thereby forming a leak-resistant seal between the lid edge and thetray edge.
 3. The leak-resistant pulp container of claim 2, wherein thelid edge is configured so that the outer wall of the peripheral channelof the lid edge applies force to the outer portion of the tray edge toforce the sealing surface of the tray edge against the sealing surfaceof the lid edge.
 4. The leak-resistant pulp container of claim 2,wherein sealing surfaces of the lid edge and the tray edge extend toinclude at least a portion of the horizontal channel walls of the lidedge and the tray edge.
 5. The leak-resistant pulp container of claim 2,wherein the inner wall of the peripheral channel of the lid edge and theinner wall of the peripheral channel of the tray edge are dimensioned toat least partially overlap in a cross-sectional plane, thereby forcingthe sealing surface of the tray edge against the sealing surface of thelid edge when the lid is secured to the tray.
 6. The leak-resistant pulpcontainer of claim 1, wherein the protrusion of the outer wall of theperipheral channel of the lid edge has a lower lip which extends inwardto keep the outer portion of the tray edge in place in the protrusion,thereby acting to secure the lid to the tray.
 7. The leak-resistant pulpcontainer of claim 6, wherein the lower lip of the protrusion of theouter wall of the peripheral channel of the lid edge is formed inseparate peripheral segments around the periphery of the lid.
 8. Theleak-resistant pulp container of claim 1, wherein inner wall of theperipheral channel of the tray edge forms a draft angle with respect toa vertical direction of the container, when upright, of between about 8degrees and about 12 degrees.
 9. The leak-resistant pulp container ofclaim 8, wherein the draft angle of the inner wall of the peripheralchannel of the tray edge is between about 10 degrees and about 12degrees.
 10. The leak-resistant pulp container of claim 1, wherein theouter portion of the tray edge is substantially flat in a horizontalplane of the container when upright.
 11. The leak-resistant pulpcontainer of claim 1, wherein a tab extends from the lid edge and beyondthe tray edge.
 12. The leak-resistant pulp container of claim 1, whereinthe tray and the lid each has a substantially oval shape.
 13. Theleak-resistant pulp container of claim 1, wherein the lid is formed ofany of the following plastic materials: high density polyethylene(HDPE), polyethylene terephthalate (PET), polypropylene (PP),polystyrene (PS), and polylactic acid (PLA).
 14. The leak-resistant pulpcontainer of claim 1, wherein the lid is formed by a thermoformingprocess.
 15. The leak-resistant pulp container of claim 1, wherein thelid is formed by an injection molding process.
 16. A leak-resistant pulpcontainer with a plastic lid, comprising: a tray formed of molded pulpand having a bottom and a sidewall forming an interior volume, the trayfurther comprising an edge extending peripherally outward from an upperedge of the sidewall, the tray edge having an outer portion; and aplastic lid having an edge extending peripherally outward therefrom, thelid edge having an outer portion, wherein the lid edge and the tray edgeeach has a corresponding lock portion configured so that one of the lockportions mates with the other of the lock portions to secure the lid tothe tray, and wherein the lid edge and the tray edge each has acorresponding seal portion configured so that one of the seal portionspresses against the other of the seal portions when the lid is securedto the tray, thereby forming a leak-resistant seal between the lid edgeand the tray edge.
 17. The leak-resistant pulp container of claim 16,wherein the seal portions of the lid edge and the tray edge are formedin an inner portion of the lid edge and the tray edge with respect tothe lock portions of the lid edge and the tray edge.
 18. Theleak-resistant pulp container of claim 16, wherein the lock portion ofthe lid edge comprises an outer wall having a protrusion which mateswith the outer portion of the tray edge to create an interference fitbetween the lid edge and the tray edge to secure the lid to the tray.19. The leak-resistant pulp container of claim 16, wherein the lid edgeis configured so that the outer wall of the lock portion applies forceto the outer portion of the tray edge to force the seal portion of thetray edge against the seal portion of the lid edge.